Donald Trump became the presumptive Republican presidential nominee this week, but a majority of GOP insiders aren't ready to commit to voting for him in November.

That’s according to The POLITICO Caucus – a panel of operatives, activists and strategists in 10 Electoral College battleground states. Fewer than four-in-10 GOP insiders said they would vote for Trump in the general election, while a quarter said they would not. The remaining 35 percent said they weren’t sure.

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The objections of anti-Trump Republicans ranged from criticisms of Trump’s vulgar language and crude behavior, to concerns about Trump’s control of the U.S. nuclear arms stockpile.

But a number of Republican insiders – both those who said they’d vote for Trump and some of those who were unsure – said they felt compelled to oppose Hillary Clinton, the likely Democratic nominee.

“I am still in shock, and my emotions are a little raw,” said a Colorado Republican, who, like all respondents, completed the survey anonymously. “I will, unfortunately, have no other choice, because there is nothing more important than stopping Hillary.”

“Don't love him; like her less,” added a Pennsylvania Republican. “I think there's going to be a lot of that type of decision making on both sides this November.”

Others cited party loyalty as a reason to unite behind Trump.

“I am a Republican,” said an Iowa Republican. “This is my party. It has spoken.”

Some of the undecided GOP insiders said they were waiting to see how Trump’s campaign style changes in the general election.

“I want to see how he behaves, what ideas he puts out there, who his people are,” said another Iowa Republican. “Right now, Hillary is a safer bet from a foreign policy standpoint, where Trump is a complete wild card. You can fix domestic policy … you f--- up foreign policy, and people die.”

“[I] won't vote for Hillary, but have voted Libertarian in the past when faced with two candidates that I frankly cannot stomach,” added a Nevada Republican. “Not afraid to do this again, but keeping an open mind that Trump can convince me he is actually presidential and not just a carnival barker.”

A number of GOP insiders insisted they won’t ever support Trump.

“As many others have said, country comes before party,” said a Virginia Republican. “I hate that we are in this position, but I could never vote for Donald Trump.”

“I can't look my kids in the eyes and tell them I voted for a foul-mouthed, lying cheater who bullies people and expect them to listen to anything I say about how to be a good human being,” added an Iowa Republican.

An Ohio Republican put it simply: “My wife would leave me.”

In addition to concerns about Trump’s character, a number of Republican insiders said Trump’s unstable temperament was disqualifying.

“I have always voted for every Republican nominee for every office on every ballot that I have ever cast. Trump will be the first candidate to break my streak,” said a New Hampshire Republican. “While I cannot stand Hillary Clinton, I am confident that she wouldn't start a nuclear war over a perceived slight from a foreign leader. I cannot say the same for President Trump.”

“First responsibility of the president: Control of nuclear launch codes,” added a Florida Republican. “Had Trump been in office in October 1962, we wouldn't be here to have this survey.”

These initial views of the insider class don’t match with rank-and-file Republican voters: Even before Cruz and Kasich ended their campaigns this week, a CNN/ORC poll showed 84 percent of self-identified Republican voters would choose Trump over Clinton in a head-to-head match-up. (That compares to 94 percent of Democrats who would vote for Clinton, which gives the former secretary of state a distinct advantage in the fall.)

“This is my nightmare,” one Colorado Republican said. “I am thinking about eating a dozen ‘Colorado cookies,’ slipping into a coma and waking up in January 2017.”

Democrats to Sanders: Get out, and help Clinton beat Trump.

The prospect of a Trump nomination has accelerated the urgency for Bernie Sanders to end his campaign and allow Clinton to turn her attention to the general election, a majority of Democratic insiders say.

“At this point Bernie Sanders can't win,” said a Florida Democrat. “That has been true for weeks now. So he needs to do the right and honorable thing and end his campaign. Every day he stays in is a victory for Trump.”

“The Democrats need to be able to begin the process of uniting the party and energizing the base. Bernie Sanders' continued candidacy does not serve that purpose,” added a North Carolina Democrat. “I think Hillary Clinton has shown a willingness to embrace the concerns that Sanders' voters care about. It’s time to let her do that.”

Some Democrats insisted Sanders’ campaign has helped the party and that he should remain in the race — as long as he remains committed to helping the party in the fall.

“I think Bernie should stay in as long as he wants, but I do believe he needs to get behind Hillary's candidacy and fully support her if the day comes when he does decide to drop out,” said a Wisconsin Democrat. “Bernie has added some important dimensions to this race, and he's been good for the discussion.”

Added a New Hampshire Democrat: “I believe Bernie's message continues to resonate and should impact the Democratic Party platform to the fullest extent possible. That may be all that it can do at this point, but I believe he has earned the right to see this journey through to the end.”

Others said Sanders isn’t a threat because voters recognize his moment has passed, despite his victory in Indiana this week.

“I don't think it makes a big difference at this point,” said a Colorado Democrat. “Aside from the inexperienced Bernie diehards, most people are pretty clear that we have our two presidential contenders now.”

These are the members of The POLITICO Caucus, not all of whom participated in this survey: